Lifting jack



HATS Ml W. C. FARNUM LIFTING JACK Filed Oct. 2C. 1923, 2 Sheets-Sheet 1VMM/www3 -fa Dec. S, V923;

Dec. 18, 1923.

` w. c. FARNUM LIFTING JACK 2 Sheets-Sheet 2 Filed Oct. 20. 1921 to imreve and simpli application led ctober 20, 1221.. Serial It'o. 502,993.

To all whom t may' cof/wem."

Be it own that 1, WILLIAM C. Fermin, a citizen of the United Statesresiding at Fitchburg, in the county of Worcester and State ofMassachusetts, have invented a new and useful Lifting Jack, of which thefollowing is a specification.

rlhis invention relates to a lifting jaclr of the type in which a screwis employed as the lifting element.

It 1s the general ob'ect of my invention the construction of l suchfting jacks, rendering them more emcient in operation and less expensivein manufacture.

ith this general object in view, important features ofmy lnventionrelate to an improved and simplied casing construction, particularlyadapted to receive and retain a considerable quantity of lubricant; to anovel disposition of the Glider-ent parts of the worm drive, permittin aworm thread to mesh satisfactorily wit a spur gear; to an improvedconstruction of liftlng nut zo-operating with nished projections withinthe post ofthe jack to insure smooth d easy motion of the parts; and toa novel detachable ste end of the tubular lifting member.

M invention also includes an improved auxi iary hook or load engagingmember for use with' loads which must be engaged near the base of theack.

My invention furt er relates to arrangements and combinations of partswhich will be hereinafter described and more "particularly pointed outin the appended claims.

A preferred form. oi' my invention is 'shown in the drawings, in which-Fig. 1 is a sectional elevation of my improved jack;

Fi 2 is a sectional plan view taken along the llne 2 2 in Fig. 1;

Fig. 3 is a plan view of the step or cap;

Fig. 4 is a front elevation of the lower portion of the jack partiallyin section;

Fig. 5 is a side elevation of the base of the jack; and

Figs. 6 and 7 are a plan view and side elevation of the auxiliary loadengaging member or hook. f

Referring to the drawings, my improved jack comprises a base 10 havin anupwardly extending flange or pro]ection 11 within which is threaded thelower end of a post 12 A tubular lifting member 13 is `\surface of theor cap for the upperadj acent the slidable in bearings in the post12 andis seated at its lower end in the recessed upward extension lei of alifting nut 15. The nut l5 and extension 14': are provided with axiallyextendin grooves 16 adapted to receive ribs 17 ig. 2) formed on theinner post.

The sides of the ribs 17 and the sides of the rooves are preferablyformed as finishe surfaces equally and accurately spaced an larly2 sothat the nut will en gage all o the rlbs in every position, thusavoiding any tendency to bend the lifting screw or to otherwise throwthe parts out of alignment. 'lhe ribs 17 may be conveniently finished bythe use of a tool having cutting edges accurately spaced andsimultaneously engaging each of the ribs, such a tool being convenientlyoperated in an ordinary shaping machine.

The nut 15 is actuated by a lifting screw 18, preferably of relativelysteep pitch and shown herein as havin a triple thread. A spur gear 19 isthrea ed to the lower end of the screw 18 and may be secured againstdisplacement by the use of a cross pm 20, extending through a hub 21 onthe gear 19 and also through the end of the lifting screw 18.

A ball race 22 is seated in the base 10 and a plurality of balls 23 restthereon and form an anti-friction thrust bearing for the ear 19. Ashoulder Ion the lower end of t e post 12 prevents upward displacementof the gear.

Al worm 24: (Fig. 4i) is mounted in a bearing 25 in the base l() withits axis forming an oblique angle with the axis of the screw 18 and gear19. The worm is provided with a suitable ball or thrust bearing 26 atits lower end and is secured in position by a locking pin 27. A suitableoperating device or handle 28 may be detachably secured to the upper endof the worm shaft, through which the operator may apply turn the wormshown hereln as double thread.

rlhe worm bearing is placed at such an angle that the portions of theworm threads ear 19 are disposed substantially vertically, and thethreads are so formed that they operatively engage the teeth of the spurgear 19. This construction is of importance, as it not onl avoids theuse of an expensive worm w eel but it also permits cons bleaniall'variation power to aving a in the position of the gear.19,without affecting the-satisfactory operation of the mechanism.

A step or cap 30 is provided at the upper end of the tubular member 13,said cap having a projection 31 fitting within the member 13 and havinga recess 32 extending transversely of the projection. A ball 33 andspring 34 are mounted in the recess 32 and the member 13 is providedwith an internal semi-circular groove 35 adapted to receive the ball asit is pressed outward by the spring 34.

Displacement of the cap is thus prevented while at the same time the capmay rotate freely in the member 13. A small opening 36 in the member 13permits the insertion of a pin or wire to press back the ball 33 whenthe parts are to be separated.

Annular recesses 37 are provided near the upper end of the post 12 toreceive packings 38 which closely engage the member 13 and preventescape of lubricant ,from the post or casing. This construction permitsthe whole interior of thepost 12 to be filled with oil or other suitablelubricant and eii'ectively excludes dirt therefrom. .e

In Figs. 6 and 7 I have shown an auxiliary load engaging device or hookcomprising a semi-cylinder sleeve-like body portion 40 having a head 41at its upper end and a projection or hook 42 at its lower end. The head41 is provided with a transversely extending iiange 43 adapted to beseated in a recess 44 in the step or cap 30. This auxiliary device isextremely useful where it is necessary to lift a load which can only beengaged near the base of the 'ack.

J Having thus described my invention it will be evident that changes andmodifications can be made therein by those skilled in the art within thespirit and scope of my invention as set forth in the claims, and I donot wish to be otherwise limited to tween portions of said base and postwhich limit axial movement thereof, and an actuating worm for said gearmounted in a bearing in the side of said base disposed at an obliqueangle to the axis of the screw, said worm accurately engaging said gearin any vertical relation of said parts.

2. In a lifting jack, a non-rotatable tubular load supporting member,means .to force said member upward, a cap for said member, and ayielding locking device detachably securing said cap to said member,said means perm1tting ifree relative angular movement between said capand-member.

3. In a lifting jack, a tubular member, a cap for said member, and meansto detachably secure said cap in said member, said member having aninternal groove near its upper end and said cap having a projectionfitting within said member and having a locking ball yieldingly mountedin a transverse opening in said projection `in position to be retainedin said groove, thereby lockin the parts together.

4. A li ting jack comprising a post, a lifting screw, a cap movablethereby, and a load-engaging member having a semi-cylindricalsleeve-like body portion an upper portion engaging said cap, and a lowerhook-like projection to engage the load, the body portion closelyfitting the exterior of said post.

In testimony whereof I have hereunto affixed my signature.

WILLIAM o. FARNUM.

